In electronic devices such as computers, cooling fans play an important role in maintaining stable operating conditions by preventing components from overheating. Often, cooling fans can include an impeller assembly mounted within a housing. The impeller assembly can include a ring magnet forming a rotor and the housing can include one or more wound stators. The interaction between the magnetic fields formed by the rotor and the stators can give rise to a torque, causing the impeller to rotate relative to the housing. When the impeller assembly is not balanced about a rotational axis, the rotation of the impeller can induce a vibrational force on the cooling fan and any surrounding structure.
These vibrations can cause acoustic noises and vibrations that are unpleasant for a user of the device. Moreover, vibrations can reduce the efficiency of the device and increase wear on bearings and other mechanical connections. The vibrations can be reduced by balancing the impeller assembly about its rotational axis during the assembly process. The balancing can be accomplished by measuring a radial acceleration for the impeller assembly while it is rotating and then adding or subtracting mass from specific areas of the rotor to achieve an acceptable balance. However, this process can be costly and time consuming, particularly in a high volume manufacturing environment.
Therefore, what is desired is a fast and efficient way to balance an impeller assembly in a cooling fan during an assembly process.